报错信息如下：
yum -y install prce
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
No module named yum
Please install a package which provides this module, or
verify that the module is installed correctly.
It's possible that the above module doesn't match the
current version of Python, which is:
2.6.1 (r261:67515, Aug 7 2010, 11:36:17)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-44)]
If you cannot solve this problem yourself, please go to
the yum faq at:
http://wiki.linux.duke.edu/YumFaq
解决思路
执行命令，找到 yum 命令的在哪：
whereis yum
yum: /usr/bin/yum /etc/yum /etc/yum.conf /usr/share/man/man8/yum.8.gz
编辑命令：
vim /usr/bin/yum
#!/usr/bin/python
# 改成
#!/usr/bin/python2.6.6
重命名命令：
cp /usr/bin/python /usr/bin/python2.6.6